Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add organvm-iv-taxis/a-i--skills --skill api-design-patternsgit clone --depth 1 https://github.com/organvm-iv-taxis/a-i--skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/organvm-iv-taxis/a-i--skills/api-design-patterns)<a href="https://agentmods.dev/skills/organvm-iv-taxis/a-i--skills/api-design-patterns"><img src="https://agentmods.dev/badge/skills/organvm-iv-taxis/a-i--skills/api-design-patterns/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/organvm-iv-taxis/a-i--skills/api-design-patterns"><img src="https://agentmods.dev/badge/skills/organvm-iv-taxis/a-i--skills/api-design-patterns.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 2 findings, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Tool Misuse · line 71 Tool parameters are crafted to achieve unintended or unsafe behavior. Parameter abuse can bypass intended safety checks (e.g. shell=True, --force, dangerous glob patterns).Fix: Validate all tool parameters against an allowlist. Reject dangerous parameter values (shell=True, --force, -rf /) and use safe defaults.
- medium Data Exfiltration · line 474 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00054 | $0.02746 |
| Opus 5 | $0.00027 | $0.01373 |
| Sonnet 5 | $0.00011 | $0.00549 |
| Haiku 4.5 | $0.00005 | $0.00275 |
Grade A, and why
api-design-patterns scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 535 lines — stays where its author put it; the contents beside it link to each section on GitHub.
API Design Patterns
Build APIs that developers love to use.
Design Principles
The Three Laws of API Design
- Predictable: Consistent patterns throughout
- Discoverable: Self-documenting, intuitive naming
- Evolvable: Can change without breaking clients
API-First Mindset
Design → Document → Mock → Build → Test → Deploy
NOT: Build → Document (maybe) → Hope it works
REST Patterns
Resource Naming
# Collection
GET /users # List users
POST /users # Create user
# Item
GET /users/{id} # Get user
PUT /users/{id} # Replace user
PATCH /users/{id} # Update user
DELETE /users/{id} # Delete user
# Nested resources
GET /users/{id}/posts # User's posts
POST /users/{id}/posts # Create post for user
# Actions (when CRUD doesn't fit)
POST /users/{id}/activate
POST /orders/{id}/cancel
Naming Conventions
| Do | Don't |
|---|---|
/users |
/getUsers, /user-list |
/users/{id} |
/users/get/{id} |
/users/{id}/posts |
/getUserPosts |
| Plural nouns | Verbs in URLs |
| Lowercase, hyphens | camelCase, underscores |
HTTP Methods
| Method | Purpose | Idempotent | Safe |
|---|---|---|---|
| GET | Read | Yes | Yes |
| POST | Create | No | No |
| PUT | Replace | Yes | No |
| PATCH | Update | No* | No |
| DELETE | Remove | Yes | No |
*PATCH can be idempotent if designed carefully
Status Codes
| Code | Meaning | Use When |
|---|---|---|
| 200 | OK | Successful GET, PUT, PATCH |
| 201 | Created | Successful POST with new resource |
| 204 | No Content | Successful DELETE |
| 400 | Bad Request | Invalid input |
| 401 | Unauthorized | Missing/invalid auth |
| 403 | Forbidden | Valid auth, no permission |
| 404 | Not Found | Resource doesn't exist |
| 409 | Conflict | Duplicate, state conflict |
| 422 | Unprocessable | Valid syntax, invalid semantics |
| 429 | Too Many Requests | Rate limited |
| 500 | Server Error | Unhandled server error |
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 11d ago First seen · 535 lines · 54 tokens per session scan A 5cef4a1318bc
api-design-patterns is a skill published in the GitHub repository organvm-iv-taxis/a-i--skills (17 stars, last pushed 15d ago), licensed Apache-2.0. It adds 54 tokens to every session and 2,746 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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